NVRAM
This is an incomplete command. However, this indicates that the running configuration will be saved on the device to a different location.
wr or copy running-config startup config
It is short for copy running-config starting-config. Running-config is the configuration of the router as you have modified it and which is currently operating, held in RAM (gone after a reboot), and you copy it to the starting-config which is in NVRAM and gets loaded by the router when it boots/ So essentially you're saving what you have now to the persistent storage so your router will still work after a reboot.
To save the current running configuration you can use the "copy run start" command. Any configurations that are made on a router will not be saved until you use this command and it will save the current running configuration to the local NVRAM. This configuration will then be used on next startup. To back up we can save the configuration to a remote TFTP server with use of the "copy run tftp" command. Always have a back up plan.
What is the purpose of using the copy tftp flash command on a router? to back up the current IOS image to a server to restore the IOS image from a server to back up the router configuration to a server to restore the router configuration from flash
In NVRAM
NVRAM is an acronym for Non-Volatile Random Access Memory. NVRAM is a type of Random Access Memory (RAM) that retains its information when power is turned off. The NVRAM is a small 24 pin DIP (Dual Inline Package) integrated circuit chip and is thus able to obtain the power needed to keep it running from the CMOS battery installed in your motherboard. It keeps track of various system parameters such as serial number, Ethernet MAC (Media Access Control) address, HOSTID, date of manufacture, etc. NVRAM is therefore a type of non-volatile memory that offers random access SYED OWAIS ALI{TECHNICAL SPECALIST}
Router(config)#Copy running-config startup-config
copy run start
to TFTP
config tftp run